Structure-evolution-designed amorphous oxides for dielectric energy storage

Abstract

Dielectric capacitors are fundamental for electric power systems due to the fast charging/discharging rate and high-power density.[1,2] Recently, rapidly increased demands of miniaturization and integration continuously challenge energy storage density of dielectric capacitors, especially for that could be compatible with the complementary metal-oxide-semiconductor (CMOS) technology, for developing energy-autonomous systems and implantable/wearable electronics, where high-κ capacitors become increasingly desirable in the next-generation applications.[3-5] However, their recoverable energy storage densities (Urec) are low in emerging capacitive energy storage materials. Here, by structure evolution between fluorite HfO2 and perovskite hafnate who have similar metal sublattices, we create an amorphous hafnium-based oxide that exhibits a giant Urec of ~155 J/cm3 with an efficiency (η) of 87%, which is record-high in high-κ materials and state-of-the-art in dielectric energy storage. The improved energy density is owing to the strong structure disordering in both short and long ranges induced by oxygen instability in between the two energetically-favorable crystalline forms. As a result, the carrier avalanche is impeded and an ultrahigh breakdown strength (Eb) up to 12 MV/cm is achieved, which, accompanying with a large permittivity (εr), remarkably enhances the dielectric energy storage. Our study provides a new and widely applicable playground for designing high-performance dielectric energy storage with the strategy exploring the boundary among different categories of materials.

Realization of High Energy Storage Performance in BaTiO3-Bi(Co0.5Zr0.5)O3 Thin Film through Defect Construction in an Amorphous Structure

“…23 As the grain/cluster size falls in a few nanometer and turns into an amorphous state, the long-range order of ferroelectric will disappear together with the emergence of a short-range order. 36,43 One can infer that this short-range order in a few nanometers of the amorphous phrase will enhance the switching of defect dipoles under the external electric field and improve the polarization. Meanwhile, with the removal of the external electric field, the dipole will return to the disordered state and exhibit a P r ∼ 0. will inevitably form an oxygen vacancy-rich area, and the pinning effect will inhibit the polarization switching of the crystalline region that may be produced in the thin film, thus resulting in the decline of polarization.…”